…Is PVC safe?
That is a question that extreme environmental groups have been using to try to scare the public away from PVC for about 15 years. Before you read any more of this article bear in mind that I am not unbiased on this issue. My family has been in the uPVC window business since 1985. We have purchased, fabricated, welded, sawed and processed this material since that time. We have handled the parts and been immersed in this material for 25 years and have been extruding the material since 1999. I’ll be the first to tell you that it’s not worth any amount of money to offer a product for the market if it is hazardous to my health, or my brothers health, or the health of our employees or is hazardous to the ultimate consumer. I’ve researched the health side and read countless articles about PVC as regards to health since 1985. I’m not a Chemist nor a Doctor, and I did not stay at a Holiday Inn Express last night.
…IS PVC safe?
The short answer is, absolutely, yes it is safe. PVC resin is make up of Carbon, Hydrogen and Chlorine, all of which are elements on the Periodic table that you studied in High School chemistry. Carbon is the basic building block of life on earth and Hydrogen is abundant in the atmosphere: we breath it every day. The major issue with PVC is the third component of the molecule which is Chlorine. Chlorine is an element that is a mixed bag. If you use prescription drugs, it is likely that you are ingesting Chlorine, or it is likely that Chlorine was used in the manufacture of the drug you have taken. If you drink tap water you are ingesting Chlorine. If you swim in a pool you are exposing your skin to Chlorine. Chlorine is omni-present in so many things we have and do and it is perfectly safe.
If it appears in a free radical form, then it is dangerous. In this state it is not inert–which means that it is very reactive with other elements or chemicals. For those that really don’t know what a “free radical” is, it is an element (an Atom) with an unpaired electron. It can be positively charged or negatively charged. Environmental extremists with no knowledge of chemistry try to paint this as an extremely abnormal thing, when it fact it is just a scientific description of an atomic state. That’s it. Nothing more.
FYI, As a matter of fact the act of breathing and creating energy for your body makes free radicals (get that, the human body creates free radicals in the normal biological chemistry that happens every minute in the process of breaking down sugars and starches to energy to do physical work. Painted another way, in the act of vacuuming a kitchen floor, the human body creates the dreaded “free radical” to fuel that activity.)
An atom can lose an electron and still not be dangerous to organic life. For example, when you create static electricity and a material “zaps” you with this energy you are basically stripping a very loosely associated electron from an element and then giving that electron back when you get “zapped”. That’s not the type of electron deficiency that I’m talking about. The electron deficiency that I am talking happens when you break a chemical bond called a ionic bond or a covalent bond between two chemical elements.
The chlorine that is used to make PVC actually comes from salt, the same salt that you use to season your vegetables. (As a matter of fact about 50% of the weight of PVC comes from salt. In the immortal words of Gomer Pyle: Shazam! don’t that just beat all…) Salt is made up of the element Sodium (Na) and Chlorine (Cl), the chemical is NaCl. The NaCl molecule is “cracked” or split up to form Na+ and CL-. When this occurs both the Sodium and the Chlorine become a “free radical” or “radical”. For this article we are focused on PVC so I’ll address the CL-. CL- is a very reactive chemical. It wants to bond to anything that it can to lower its energy state. If it happens to be around human cells, then it will try to bond with those cells. Herein lies the problem. When it tries to bond to human cells, it can cause a cancer. Infrequent exposure to CL- is not going to cause a problem, but chronic exposure to CL-will cause cancer in some individuals.
After the CL- is created it is reacted with ethylene or acetylene to produce VCM and then ultimately PVC resin. This VCM is a gas and also has chlorine in a radical state. This is the material that has created all the controversy with the Greenpeace environmental group. Some years ago the VCM producers were not aware of the carcinogenic nature of VCM and people were chronically exposed to the gas. Some of these people developed cancer. And it has been this experience which has caused most of the issues with PVC. There is another issue that has surfaced about PVC which is the plasticizers that are additives put in PVC to make it soft. This, in my opinion, has been blown out of proportion (and so has the VCM issue, for that matter). Flexible PVC was used in intraveneous bags used in blood transfusions for tens of years and has helped save the lives of millions of people. Now, all of a sudden, it’s been deemed as an environmental issue by groups such as Greenpeace. The fact is that when the VCM has been processed to form PVC, then the molecule becomes stable and inert. At this time the PVC molecule is very safe to process and handle. Put another way, when the PVC leaves the VCM processing plant, it is completely safe.
For a good article on the formulation.. .read more
At the risk of being repetitive the VCM gas is an interim step on the way to the fully defined PVC molecule. The VCM is processed one more time to create cPVC and uPVC. First, the raw material VCM is pressurized and liquefied, and then fed into the polymerization reactor, which contains water and suspending agents in advance. Through high-speed agitation within the reactor, small droplets of VCM are obtained. Next, the initiator for polymerization is fed into the reactor, and PVC is produced by reaction under a low pressure at 40 – 60°C. (1) When this process completes the PVC is created and it is at this point the PVC becomes inert, and subsequently not a hazard to human health. The word inert means that the molecule is very stable at ambient temperatures and pressures. This property is what makes the product so suitable to window and door applications.